Effect of litters from Juglans mandshurica and Larix gmelinii on the growth of J. mandshurica seedlings.

Abstract

We conducted a pot experiment to examine the effects of different proportions (CK: no litter; H₁₀L₀: Juglans mandshurica 10 g; H₇L₃: J. mandshurica 7 g + Larix gmelinii 3 g; H₅L₅: J. mandshurica 5 g + L. gmelinii 5 g; H₃L₇: J. mandshurica 3 g + L. gmelinii 7 g; H₀L₁₀: L. gmelinii 10 g) of J. mandshurica and L. gmelinii litter on nutrients and phenols content in the substrate, and on the growth and physiological characteristics of J. mandshurica seedlings. The results showed that litter input significantly affected ammonium nitrogen, available phosphorus, and phenols contents in the substrate. The content of substrate nutrients (except available phosphorus) was the highest when J. mandshurica and L. gmelinii litter were mixed in equal proportion (H₅L₅). The total phenols and water-soluble phenols contents in the substrate decreased as the proportion of L. gmelinii litter increased, while those of H₀L₁₀ treatment were significantly reduced by 22.7% and 25.3%, respectively. The addition of L. gmelinii litter could effectively promote the growth of J. mandshurica seedlings. The synthetical allelopathic index (M_R) of H₃L₇ and H₀L₁₀ treatments was higher than that of H₁₀L₀ and H₇L₃ treatments, with the highest value under H₀L₁₀ treatment (M_R=-0.07). Litter inputs significantly increased net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, and transpiration rate of J. mandshurica seedlings. The content of malondialdehyde (MDA) was the highest and net photosynthesis rate was the lowest in CK. Seedlings under H₀L₁₀ treatment had the best growth, with the lowest MDA content, and the highest net photosynthesis rate, which significantly increased 101.6%. The addition of L. gmelinii litter could alleviate the autotoxicity of J. mandshurica seedlings and stimulate their growth. The high litter proportion of L. gmelinii promoted the growth and physiological characteristics of J. mandshurica seedlings.